Magnetic graphene oxide-containing chitosan‑sodium alginate hydrogel beads for highly efficient and sustainable removal of cationic dyes.

Developing recyclable and efficient adsorbents for cationic dyes removal from wastewater is crucial for ensuring green ecology and drinking water safety. Herein, we demonstrated a novel magnetic gel bead adsorbent that was synthesized by employing graphene oxide (GO) modified FeO as magnetic nanoparticles doped sodium alginate (SA)/chitosan (CS) gel (SA/GO@FeO/CS). The GO@FeO sample was prepared based on GO by the chemical co-precipitation method, which not only reduced the aggregation of FeO but also increases the specific surface area of the composite gel beads. The prepared gel beads were used to adsorb methylene blue (MB), neutral red (NR), and safranine T (ST). The experimental results showed that the adsorption capacity of SA/GO@FeO/CS gel beads for MB, NR, and ST reached 21.325 mg/g, 44.654 mg/g and 44.313 mg/g. After five recycles, the removal rates could still reach more than 90% of the original, exhibiting a high recovery rate. Therefore, this paper provides a strategy for the preparation of high efficiency and recyclable cationic dye adsorbents with a large specific surface area.